Banshee
by Center of the Galaxy
Summary: Lydia just wants a night to celebrate after narrowly surviving the pack's latest brush with death. Crowley has other ideas. Lydia is the key to Crowley's latest scheme and it's up to the pack, along with Sam and Dean, to stop it. *post season 3A Teen Wolf, later season 8 Superatural, slow build Stydia*
1. Celebrate

_**Author's Note:**_ _I've wanted to write a Supernatural/Teen Wolf crossover for a while now. I wasn't sure how to do it. I'm not really even sure where this idea came from. I set this after season 3A in Teen Wolf and in later half of season 8 in Supernatural. I hope you enjoy it!_

* * *

" _We went out last night_

 _Like we swore we wouldn't do."_

— _Kenny Chesney, "Out Last Night"_

* * *

Sneaking into bars isn't hard for Lydia Martin.

Her good looks and well-made fake I.D. are usually enough to get her in any bar of her choice. Tonight though, the bar she's chosen isn't too crowded and there's not too many staff. It's a local bar, just twenty minutes outside of Beacon Hills, resting off a dirt road.

"Should we really be doing this?" Stiles asks her, glancing nervously at the other patrons in the bar.

She wants to laugh at him. Here he is, a fearless man when it comes to handling werewolves and other crazy supernatural creatures, yet he's reduced to a cowardly little boy when it comes to breaking the rules a little bit and getting a drink.

"It's fine." She dismisses his concerns as they take a seat at a table far from the watchful eye of the female bartender. "You've had drinks before."

"Yeah," He shrugs, jamming his hands in his pockets. Then, a little bit under his breath adds, "Just never so conspicuously before."

Lydia chuckles at that, grinning and feeling like she can finally breathe. The weight of the world is no longer on her shoulders. The pack is safe and life is good. She deserves one night out and while Alison was her first choice— _Lydia, sorry, I've got plans with Isaac! You understand, right?—_ ending up at the bar with Stiles isn't too bad.

"Then, just get a Coke." She smirks at him.

"Well, one of us has to drive." He mutters as he gets up and goes to the bar. He returns a few seconds later with a beer for her and a Coke for him. He begins to sip his Coke and she takes a swig of her beer.

"Relax, Stiles." The Banshee places a hand on her wrist, smiling openly at him. "Your dad won't catch us."

"How'd you find this place anyways?" He asks her, sinking back into his chair. He takes in the subdued décor and the light strains of classical rock that can be heard and then glances at her. The strawberry blonde is radiant in a white flowery top and a pair of jean capris. Her hair is back in a braid and she's wearing less makeup than usual, though in his eyes, she's still as radiant as the day he first laid eyes on her in third grade.

"Alison and I were driving and we found it." Lydia remarks casually. "She and I don't come here often, but sometimes it's nice to get out of Beacon Hills."

"I hear you." Stiles seconds, taking a sip of his Coke.

It's been a rough couple of weeks and though they came close to losing one another, the pack is safe once again. That, alone, is worth celebrating.

"Hey," Stiles begins softly, his hands gripping the bottle of his Coke. He finally meets her eyes and Lydia can see some hesitation in those hazel eyes. "Why'd you ask me to come with you?"

The banshee shrugs, trying to play it off casually, "We just never get a chance to hang out, you know, other than when we're in imminent danger."

He laughs at that, his body posture relaxing.

"Why?" Lydia presses. "Did you have other plans—?"

"No," He interjects quickly, "I just . . ." His voice fades and he lets whatever thought he had go.

The door opens, a bell dinging and Lydia glances at two men standing in the doorway. A shiver runs under her skin and she stiffens, suddenly unable to look away. The taller one is sickly, skin pale and beads of sweat on his forehead. His longer hair sticks to his skin and though he's standing upright and confident, she can see how close he is to death, how easy it would be for him to fall into that eternal darkness.

But the shorter one, the one with vibrant green eyes and a leather jacket, she can sense something in him. Something dangerous, something about to snap—she realizes it in a second.

They're hunters.

"Lydia?" Stiles has his hand on her shoulder, gripping it, and she realizes a second too late that she'd been on her way to go to them. "Lydia, what is it?"

Part of her wants to scream. The other part wants to cry.

The one thing she knows for sure is that these two are dangerous and she and Stiles need to get out of here before something bad happens.

"We have to go." She manages to say and her voice is quivering.

Stiles, thank goodness, doesn't question her. He simply takes her hand in his and moves them towards the door.

They don't make it that far.

The door bursts open and before the teenager can even comprehend what's going on, she finds herself being propelled backwards by an invisible force. She and Stiles hit the counter hard and all the oxygen from her lungs is pushed out.

"Stiles!" She shouts, but he's unconscious, having hit his head. She forces herself to breathe and tries not to panic as a man in a jet black suit and a grey tie leans in the doorway, a smirk on his lips.

"So, boys," It takes her a second to realize that he's talking to the two men that came in a few minutes earlier. "Thought you could beat me to her?"

"Crowley." The sickly one hisses, sounding not very sick at all. He pulls out a gun from seemingly nowhere and Lydia curses her bad luck. Of course, out of all the nights in the year, the one she chooses to go out on is cursed.

"Stiles." She tries to lift him, but he's heavier than she expected and it takes her a few tries to get them both standing, his arm slung around her neck. She can see a back door, behind the bar and she slowly, and as inconspicuously as she can, tries to get the two of them out.

She's almost at the backdoor when the crisp accented voice reaches her ears, "And where do you think you're going, Banshee?"

The man in the suit chuckles darkly at her perplexed expression.

"Yes, sweetheart," He coos. "I know exactly what you are."

"Crowley." The man with the green eyes hisses, getting the bearded man's attention once more. The sickly man stares at her though, as if he's finally putting the last piece of a puzzle together.

"Stiles," She whispers, wishing once again that he would wake up so they could get out of this situation. "C'mon." She fumbles with the latch on the door, only to find that it's—

"Locked, sweetheart." The man in the suit is beside her now. His burning hand grazes her cheek and she shudders involuntarily. He gestures to the two men before her, unconscious on the floor.

"Who are you?" She growls, because no, this man will not intimidate her. He may know what she is, but she refuses to be afraid. She has a pack to defend her and she won't let herself play the damsel in distress without a fight.

"Name's Crowley, love." He smiles, teeth too wide, lips tilted upwards sinisterly. "But you can just call me the King of Hell."

The next she knows, there are men beside her, pulling Stiles from her and she's struggling, fighting with all her might, screaming for help, for her pack, for someone to save her.

And then there's a sudden pain on the back of her head and then there is nothing.

Darkness.

* * *

Stiles awakens to a man with vibrant green eyes staring down at him.

"Hey, you okay, kid?"

His head hurts, a dull throbbing in his temple. He rubs it absently as he tries to piece together what's happened. The bar is in shambles. Shattered glass sparkles on the floor from the dim light. Chairs are broken, tables are overturned—the whole place is a mess.

"Lydia?" He glances around the area, trying to catch a glimpse of her strawberry blonde hair.

"He's got the girl, Dean." The man with longer hair sighs. "If we don't get her back—"

"He'll kill her," Dean replies, pacing the length of the floor. "I know, Sam." He gestures to Stiles. "Now that he's awake, we can go—"

"Lydia?" He rises up shakily from the ground, his head pounding.

The two men share a knowing glance and Stiles curses under his breath.

"She's gone, isn't she?" He asks, already knowing the answer. "The man in doorway." His mind starts racing a mile a minute. He needs to get out of here, needs to get back to Beacon Hills and back to Scott, back to the pack. Together, they can go and save her—

"Where are you going?" Dean grips his shoulder and stops him from leaving. "Look, kid—"

"Stiles." The teenager interjects sharply. He hasn't been a kid since the night that Scott got bit.

"Stiles," Sam says softly, a soft smile on his lips. He projects an aura of ease and calm. "My brother and I, we're the ones who can get Crowley." He stands up, swaying heavily to one side, causing Dean to support him.

"Yeah, well, you can barely stand, so somehow I doubt that." He mutters bitterly. "You don't know anything—"

"You're part of a werewolf pack." Dean spits out quickly and Stiles eyes bug out slightly.

"And you two must be hunters." Stiles concludes. That is why Lydia was so afraid of them. She must've sensed something about them and they were just about to leave when the man in the suit showed up.

"We knew Crowley was coming after Lydia." Dean tells him, eyes downcast and regretful.

"So, what? You just let it happened?" Stiles wants to punch something. He wants Scott here. Scott can take control; Scott can give him some direction. He needs his best friend here because if Lydia dies—

"We were going to come talk to your pack," Sam insists quietly. "But, we weren't sure how to approach all of you." With a rueful grin he adds, "We are hunters."

"Stay away from us." Stiles hisses, summoning up every inch of righteous fury within him as he comes nose to nose with Dean, a hunter who could probably end him with just one punch.

"Stiles, we're not trying to start anything—!" Sam insists, but Stiles has heard enough.

"Stay away from us!" He shouts once more, slamming the bar door behind him. Thank God, his Jeep is still here and before he knows it, he's back on the road, flooring it on the way back to Beacon Hills.

He just hopes Lydia will still be alive by the time he gets back to the pack.

* * *

"Hello, love." Crowley whispers as Lydia blinks her eyes open. The world swims into view and she winces as her head throbs.

The man in the black suit—Crowley—is sitting on a throne before her and she wants to laugh at the absurdity of it. Who does this guy think he is, after all? And calling himself "The King of Hell", what kind of joke is that?

So, Lydia settles for holding her tongue and glaring at him, because no, she will not be intimidated; she will not be afraid.

"Ooh, scary," Crowley chuckles running a hand through her hair. "Tell me, Banshee, do you always look like that?"

"What do you want with me?" She struggles against the ropes, binding her to this wooden chair. It burns as it rubs against her skin and she lets out a hiss of pain.

"You, Banshee," He smiles now, openly and a chill runs up her spine. "You're my secret weapon." He snaps his fingers and the door opens, a man in a trench coat is dragged in, blood dripping from his temple.

"Oh my God." She whispers as cerulean blue eyes meet hers.

"Between you and the angel," He gestures to the man in the trench coat. "I'm sure you'll be able to figure it out." He unties her ropes and she resists the urge to sprint to the door, trying to escape. "Have fun, Banshee." He winks at her before moving to the door. He stares at her for what feels like an eternity before it finally closes behind her.

"You're the banshee?" The man in the trench coat asks, slurring his words, as though from blood loss.

"Yes." Lydia replies. "Are you okay?"

"I will heal." He replies cryptically.

"Great." She whispers. "Know how to get out of here?" Aside from the door,

she doesn't know if there's another viable escape route.

"Once I'm healed," He groans, moving to sit up. "We will get out of here."

"So . . . we wait?" Lydia murmurs, not liking this plan one bit.

"We wait." The man in the trench coat concurs, before his eyes fall shut once more.

Now, she just needs to figure out what Crowley wants with her and then get out of here alive. It should be easy.

She hopes.

* * *

 _ **Author's Note:**_ _Next chapter, Stiles gets back to the pack and Cas and Lydia team up to escape. Please review if you have a moment._


	2. Escape

_**Author's Note:**_ _Lydia and Castiel team up, go!_

* * *

" _There are no happy endings._

 _Endings are the saddest part,_

 _So just give me a happy middle_

 _And a very happy start."_

― _Shel Silverstein, "Every Thing on It"_

* * *

Lydia faces the man in the rumpled trench coat and tries to steady her breathing. She may be a prisoner, trapped by the self-proclaimed King of Hell. She may be hopelessly far from the pack and their protection, trapped with a stranger. But there is one thing Lydia Martin knows for sure—she's strong and stubborn and she will figure this out.

First things first, the only door out of the room where she is currently being held captive is locked. Crowley probably has the key. There are no windows large enough for her to break and escape through. Darkness is the only thing that filters into the room, meaning she has no idea how far away she is from Beacon Hills.

Crowley had wanted her and the guy to figure something out. What exactly did he mean by that? She was taken because she is a banshee, but other than that, what did he want from her?

"I'm Castiel." The man mutters, wincing as he presses a finger to his temple.

"Lydia." She replies softly. "You know anything about why we're here?"

Castiel pushes himself up from the floor and sways a bit before steadying himself. He frowns before adding, "The wards here," He gestures to what looks like scribbles on the wall. "They're suppressing my powers."

"Powers?" She echoes.

He blinks a few times at her, as if waiting for her to comprehend something; she does not.

"I am an angel of the Lord." He replies solemnly.

Silence reigns for a few minutes.

"An angel?" She repeats.

"Yes."

"Like a halo and wings type angel?"

"Halos are a human invention—" He tacks on and she shakes her head, trying to wrap her mind around this.

"Angels are real?" She doesn't really buy it. If there were angels, then why hadn't they helped protect her and the pack? Besides, the man before her was clearly injured. Angels couldn't get hurt, right?

"Yes." He grimaces.

"Do you know why we're here?" She asks, putting the angel issue on the backburner. She can't handle another revelation right now. She just needs to get out of here and back to Beacon Hills. Once she's safe, she can try to comprehend angels.

"Crowley wishes to unlock the vault to an ancient weapon."

"A weapon?" She echoes, running a hand through her hair. "Seriously? What kind of weapon—?"

Castiel's brow furrows and his voice deepens, "A supernatural one. One with the power to eliminate all threats in his way."

"But why am I here—?"

"He needs a banshee." Castiel explains softly. Then, seeing her distressed gaze, he adds, "To get the vault open, he requires keys. A banshee, an angel and the third key is yet unknown to him."

Lydia shakes her head, shaking her hair a bit out of the elaborate braid she had put it into. She needs to wrap her hand around this and start working on a solution. Staying here, being at the mercy of Crowley—it'll get her killed.

Meeting vivid cerulean blue eyes, she orders, "We're getting out of here now."

"But how—?"

"I don't know," She confesses softly. "But we can't just stay here. Do you have any control of your powers?"

"As I said the wards—"

Instantly, a thought dawns in her mind. She reaches for a table off the tables and the pitcher of water Crowley had left them. She moistens the towel and tosses the water on the wall. Gritting her teeth, she begins to scrub the red paint off.

"My name is Lydia, by the way." She realizes she hasn't said really anything to him yet.

"Lydia." Castiel comes to stand next to her, taking the other side of the towel. "Let me help."

With that, they begin to scrub the vigils away.

* * *

"Here." Alison hands him a cup of steaming tea and Stiles stares down into it. The heat burns his cheeks, but he doesn't even flinch. He's numb, after all. Losing Lydia . . .

"Stiles." Scott shoots him a sympathetic glance before coming into the dining room.

"Anything?" Stiles presses, hoping for some sort of news, any glimmer of hope that will give him the strength to get through the night—a never ending night that only her bright smile will break.

"Your dad has put out an APB on her." Scott informs him, placing a hand on his shoulder and offering his support.

"But no leads?" Stiles continues, his hands are white-knuckling the teacup in his possession.

"Isaac is out there too," Scott adds with a tired grin on his lips. "We will find something."

"We will find her." Alison corrects softly.

"I know." Stiles' voice breaks, as the grief bubbles up within him. She could be dead right now, her beautiful eyes staring upward forever at nothing. Her crimson cheeks could be ashen and her body might be nothing but a corpse now. There's a strong possibly that Lydia Martin might very well be—

There's a knock on the door.

Alison shares a wary look with Scott.

He nods and a dagger slips out of her sleeve. She moves to the front door and shares one more glance with her former boyfriend before opening it.

"Easy!"

Sam and Dean—the two hunters from the bar stand in the doorway—their hands raised in submission.

"Who are you?" Alison hisses as Scott comes up behind her, ready to step into the fight if she needs it.

"Wait," Stiles rises from the table. "I know them. They're from the bar."

"The hunters?" Scott questions and Stiles nods his head. Then, staring at the two men in the doorway, he growls, "Why should we let you in? You kill people like me—"

"We kill monsters." Dean interjects sharply.

"Scott," Alison cautions, lowering her blade. "They might know what happened to Lydia."

"They do know," Stiles replies. "They were coming to get her themselves."

"Not true!" Dean interjects as Scott snarls, fangs descending and Alison's blade is once more pointed at them and ready to kill.

"We can talk this out." Sam counsels, voice weak as he grips the doorway. Beads of sweat rolls down his forehead and suddenly, he looks as if he's about to collapse. His knees do buckle and Dean catches him.

"Sammy!" Without an invitation, Dean pushes their way inside and places Sam at the dining room table. "You okay?"

"M'fine." Sam slurs, eyes fluttering back open.

"I never should've let you come." Dean shakes his head, voice defeated. "Charlie could've—"

"If Crowley gets what he wants," Sam starts, voice growing stronger. "We're all screwed."

"What do you know?" Alison demands, coming to stand next to Stiles.

"You're okay?" Dean addresses Sam, placing two fingers on Sam's pale neck to check his pulse. .

"I'm fine." Sam shakes off his fussing. "We're running out of time."

"Is Lydia going to be okay?" Stiles practically shouts, the worry surging through him, consuming every piece of him. He doesn't know who these hunters are or if he even really trusts them, but Lydia's life is on the line and they're desperate.

"Sit down." Dean commands. "It's a long story."

* * *

It feels like a small eternity, but eventually, they have scrubbed all the wards off in this room. Lydia practically beams as she meets Castiel's gaze.

"So," She starts, wanting to jump for joy. "Better?"

"Indeed." Castiel replies quickly, flexing his hands and wearing a small smile of his own.

"We can get out of here now, right?" Lydia presses, hoping to God that the answer is yes. She's slowly going stir-crazy in this room. She's not sure how much time has passed since she's arrived here, but she isn't willing to stick around and ask Crowley that when he comes back.

"We can." He holds his hand out in front of him and grits his teeth as he makes the pitcher they used levitate. It then falls to the ground with a thud. "Or at least," He concedes softly, "We can try."

"You're not up to your full-strength." She concludes and he shakes his head.

"No." He sighs.

"We'll have to risk it." She tells him sharply. "Better to try to escape than to wait here and hope we get another chance."

Castiel regards her for a few moments before nodding to himself. He holds out his hand and she immediately takes it.

"Close your eyes." He whispers and she complies.

And then she's flying away.

* * *

"Sir?"

Crowley glances up from his latest field reports and meets the wary gaze of the demon standing in his doorway.

"What?" He growls and the demon before him flinches, his gaze dropping to the floor.

"Sir," The demon shifts uncomfortably before him, obviously afraid to impart whatever knowledge he has. "Sir, I—"

"Spit it out!" Crowley snaps.

"The banshee and the angel," He meets Crowley's gaze fearfully. "They've escaped."

Crowley kills him of course. There is no such protocol in Hell about not killing the bearer of bad news and as the King of Hell he has appearances to keep up, but in truth, he had hoped the duo would escape. He's not the only player in this game and he knows that he will get what's rightfully his. Let Castiel and the banshee think they've won. Let them run off to their respective friends rejoice.

In the end, Crowley will get exactly what he wants.

"Just a matter of time." He muses, glancing at the bloody body on the floor.

He just needs a bit of patience, that's all.

* * *

 _ **Author's Note:** Next chapter, the backstory on the weapon. Please review if you have a moment. Thanks! _


	3. Found

_**Author's Note:**_ _Thanks again for all your kind words! I'm glad you all are enjoying this crossover as much as I'm enjoying writing it._

* * *

" _You cannot swim for new horizons until you have courage to lose sight of the shore."_

― _William Faulkner_

* * *

When Lydia opens her eyes, she's standing in the middle of a field, dirt crunching under her shoes. The grass blows gently in the night breeze. The moon above her glows brightly, but she can't make out any stars.

She's in the middle of nowhere, it seems. But at least, she's safe.

Castiel sinks to his knees, his breath coming in pants.

"Hey," Lydia places hand on his shoulder, trying to steady him. "Are you all right?"

"Fine." He assures her, though his voice is weak and it makes her more worried than reassured. He rises shakily from the ground, swaying a bit as he grits his teeth from some unnamed pain.

"Okay," She lies, and then taking in her surroundings, she frowns. She doesn't recognize this area, doesn't know far she is from the bar or Beacon Hills. "We just need to get walking."

"To where?" He asks, coming to stand by her side.

Lydia smirks, "Forward, I guess."

And that's when she starts walking.

* * *

"So," Scott's mind is reeling, unsure of whether he can fully process this information. He faces the two hunters seated at the coffee table, his arms crossed against his chest as he leans against the wall. "Run this by me again?"

Dean sighs as he glances at his brother's pale figure. Sam has seemed to have gotten worse since the duo arrived at the house. His forehead is beaded with sweat, his hair clinging to it and his eyes are glassy and unfocused. The man is sick, no one could deny that.

But Scott can sense that this more than a simple case of influenza. There's something about this illness that the hunters aren't disclosing. Something supernatural maybe?

"Crowley is the King of Hell." Dean repeats, voice weary.

Alison shakes her head in disbelief.

"A demon?" She asks and Sam nods his head, "Right, okay, because we haven't face enough weird stuff." She huffs out a laugh, more cynical than calming.

"And he took Lydia because she's a key to open the vault to get to this mystical weapon." Stiles is up and pacing the length of the floor, a hand running through his hair. He's processing every detail in his mind, trying to come up with the solution that will save the strawberry blonde that he cares so deeply for.

"A weapon that will destroy anything and anyone that opposes Crowley." Dean completes.

"Though we don't know exactly what the weapon looks like or how it functions." Sam adds in a breathy voice. His cheeks are almost burnt in color, an awful maroon shade.

"But we do know that Crowley knows where the weapon is and he knows how to activate it." The eldest Winchester answers.

"Great." Scott sighs. "So, we really know next to nothing."

Alison comes to her former boyfriend's side, placing a comforting hand on his shoulder.

"And we should trust you two?" The huntress poses the question to the men. She doesn't know the Winchesters. They are the kind of hunters she's worked with before, that she's trained with. They are wild, unfocused, but from what she can make out, they are highly skilled and they know their lore. They do know a lot more than she's ever been told. Hell, Heaven and angels? Who knows that they existed? It is crazy to think about actually how little she really knows about the world.

Dean smiles a self-assured smirk, chuckling darkly, "Do you really have a choice?"

"Dean," Sam admonishes. Then, he turns his gaze to the teenagers in the room. "Look, you have every right not to trust us—"

"No, really?" Stiles interrupts sarcastically.

"But at this point, it really wouldn't hurt you, right? Your friend, Lydia, she's still out there—"

There's a knocking at the front door.

Instantly all conversation dies down and Alison motions for silence, placing a finger against her lip. She reaches for her blade and Scott nods at her, claws descending. Together, they move towards the front door.

"One." Alison mouths and Scott nods his head.

"Two."

They open the door on three, ready to maim whatever enemy is there. Except, it's not an enemy.

"Lydia?" Alison calls out, hesitant, unsure if her eyes are playing tricks on her.

But no, her best friend is standing there, her eyes tearing up, a brilliant smile spreading across her peach lips.

"Lydia!" Alison shouts now, dropping the blade and embracing her friend in a hug.

"Alison!" Lydia is crying now, the two girls practically jumping up and down from the sheer joy and relief at seeing each other.

"Cas?" Dean calls and the man in the rumpled trench coat standing behind Lydia waves sheepishly.

"We escaped." He states the obvious and Dean chuckles.

"Come inside." Scott takes charge, ushering everyone back to the kitchen.

"Lydia?" Stiles can hardly believe she's okay. Yet here she is, standing before him, as radiant as ever.

"Hey." She grins at him, warm and bright and it's like his lungs learned how to breathe again because she's alive and she's safe.

And before he knows it, he's taking her into his arms and holding her tight enough to reassure him that she's okay.

"I almost lost you." He whispers, her head coming to rest upon his shoulder.

"I know." She replies softly. "I'm okay, Stiles."

When she breaks away from his embrace and moves back to speak with Alison, he tries not to let the disappointment on his face show. His arms feel so cold without her, so empty. Yet, the important thing for him to keep in mind is that she is alive and safe.

That's all that really matters.

The Winchesters are talking to the man in the trench coat, voices low and faces drawn. Whatever the man is relaying to the two hunters isn't putting their mind at ease. If anything, it's worrying them more.

"Stiles?" Lydia calls softly and he meets her gaze.

"Yeah?"

"Don't worry." She takes his hand in hers, holding it tightly.

But he can't help but worry because it's Lydia.

But it's also because he knows that whatever is going on, it isn't over. Not by a long shot.

It's only just beginning.

* * *

"Sir?"

Crowley glances up from the volume of medieval texts and meets the gaze of the young woman standing in the doorway. She holds a report in her hand and he grins upon seeing it.

"You have more news concerning the weapon?" He ventures a guess and the woman grins.

"I've got much more than that, Your Majesty." She enters the room and hands him the report. He opens it and scans the first few pages.

"Well, well," He chuckles lightly. "You figured out the third key."

"Indeed, Sire." She chirps.

"Good work." He commends her and she bows before hastily making an exit.

The blood of a banshee, an angel, and an alpha werewolf—how perfect! And really, how convenient. By letting the banshee and the angel go, they surely will lead him to the werewolf pack in Beacon Hills.

It's killing two bird with one stone.

He really does love being efficient.

And in no time at all, he'll be able to make his move.

* * *

 _ **Author's Note:**_ _Next chapter, Stiles/Lydia fluff, pack bonding and sick!Sammy! Please review if you have a moment. Thanks!_


	4. Safety

_**Author's Note:**_ _I'm back! I was asked a few questions so I'll answer them. The only pairing this story will have is Stydia and that will be a slow build. As for the reason that Alison doesn't know the Winchesters, I will address it. Hope you enjoy this chapter!_

* * *

" _I guess what scares me the most now is the thought that I won't be able to protect you."_

― _Julia Hoban_

* * *

Lydia tries not to let the residual panic overtake her as she lies in her bed that night. She keeps her breathing low and even, trying to steady her wildly pounding heart, but to no avail. Somewhere, there's a demon king after her, ready to kill her all for the sake of powering up some ancient weapon. No matter how many times she tries to keep her mind blank, his smug expression appears in her mind's eye, his voice whispering in her ear, _banshee_.

She sits up and glances at her clock—2:15 am.

Grimacing, she tosses the sheets off of her bed and places her bare feet on the cool wooden floor. Her mother is out of town and the house seems scarier than she remembers it, even though she knows the house is locked and as secure as she could make it. The Winchesters had even put sigils and salt on the windowsills, some sort of protection from demons and other things that went bump in the night.

It does little to reassure her though.

Flicking on her room light, she glances down the long hallway. She feels like she's five years old again, afraid to go down the corridor for the fear that some ghost will pop out from around the corner and kill her.

There's a sound that comes from downstairs and suddenly, the young woman freezes. She waits again and she hears it again, a sort of shuffling coming from the living room and the dread within her escapes from its cage and courses through her veins. Returning to her room, she glances around for a weapon of some sort to defend herself. She settles for a heavy chemistry textbook, but she admits to herself that this isn't the best weapon to have on hand. Pulling her phone out, she quickly punches in Scott's number, only to get his voicemail.

"Scott," She whispers, trying not to let the sheer panic leach into her tone, "I'm trying not to freak out, but someone is downstairs in my house. Please come."

Carefully, she moves downstairs, doing her best not to make any noise herself. She needs the element of surprise on her side and hopefully, she'll be able to incapacitate whoever, or whatever, is down there before making a break for it. It might not be the best plan, but it's what she's got.

There's something moving under the pile of blankets on her couch and Lydia grits her teeth, trying not to freak out completely. She comes as close as she can manage and then is about to slam the textbook down when suddenly, the blankets are thrown off and there isn't a monster under the covers it's—

"Stiles!" She exclaims and suddenly, his eyes are wide open and she can't help but drop the book in shock.

"Ow, Lydia!" He shouts, rubbing his head from where the textbook collided with his skull. "Why did you do that?"

"What are you doing hiding under my covers?" She snaps, punching him in the shoulder. "How did you even get in here?"

He chuckles somewhat at her perplexed expression, "Lydia, I know you hide the spare key under the ceramic cat."

"So, what?" She huffs, her racing heart pounding within her chest. "You just break in without telling me?"

Stiles glances away, muttering softly, "I just was . . . worried."

She sighs somewhat, then takes a seat beside him. Though he nearly gave her a heart attack, she can't help but admit that she feels better knowing he's here. Resting her head on his shoulder, she closes her eyes and tries to pretend like she isn't being hunted down by a demon king or that her friends are once again in danger. In this moment, she's just a teenager, taking comfort from someone she cares for.

"Lydia?" Stiles' nudges her and she opens her eyes, meeting his gaze. His brow is furrowed and he regards her with a bit of worry in his gaze. "You okay?" He grips her hand within his own and she smiles softly.

"I'm glad you came."

He doesn't say anything for a few moments and she shuts her eyes, letting herself be fully present in this moment.

"Lydia?"

She doesn't open her eyes, the rush of adrenaline now crashing. She's tired and needs to get back to her bed and get some rest. Who knows what the next few days would be like? She needs to get as much rest as she can.

"Yeah?"

He huffs out a chuckle, and then squeezes her hand within his own.

"Nothing."

Together, they just sit there, savoring each other's company.

* * *

"You need to take some medicine."

Sam glowers at his brother, feeling like a petulant child then the adult he is.

"Don't give me that look," Dean snaps, pulling out a bottle of Ibuprofen and placing it on the small wooden table. "Last thing we need is for your fever to spike." The eldest Winchester parcels out the pills and hands them to Sam.

"We need to find Crowley." Sam tells his brother before dry swallowing the pills. He grimaces as they go down but then glances down on the books he's dragged in from the car. He needs to figure out more about this weapon and how to stop it before Crowley got it operational.

"We will," Dean assures him with an easygoing grin. "You just need to get some rest—"

"I've got the spare bedrooms made up," Alison informs them as the young huntress comes into the kitchen. She's in her sweatpants and a long, loose top. She's clearly ready for bed, but she does her best to keep herself alert and awake. "Is there anything else you need?"

"No," Sam replies softly. "You've done so much already."

"I do have a question though?"

Sam nods, gesturing for the chair next to him.

Sitting down, she asks, "How is it that I've never heard of you two before?"

Sam shares a glance with his brother, who shrugs.

Alison continues, "I mean, I know most of everyone in our community—"

"We're not involved in your community," Dean informs her with a smirk. "Our Dad was kind of off the grid. The people we know just really work on their own."

"Is that so?" The young huntress remarks, rubbing her eyes. She tries to suppress a yawn, but fails.

"You should get some rest." Dean comments and Alison rises from the chair, nodding her head.

"If you guys need anything—"

"Go get some rest." Sam order softly and she chuckles before disappearing down the hall.

"They're all pretty relaxed," Dean remarks. "You know, considering the fact that the King of Hell is targeting them."

"Sounds like it isn't the worst thing they've been through." Sam flips through the pages of the book, trying to focus his gaze enough to be able to read the small print. "I only got a bit from Scott, but for teenagers, it's a miracle that they've survived."

"Yeah." Dean says quietly.

Sam opens his mouth to say something, but a cough suddenly wracks his body, stealing all his breath and causing his vision to blur.

"Easy, Sammy, breathe," Dean rubs circles on his brother's back, trying to ease the passage of oxygen into his little brother's lungs. "Just hang on."

The coughing fit soon passes, but it drains all the energy from Sam and Dean sighs softly.

"C'mon, let's get you to bed."

"I need to get through this chapter—"

"Bed, Sam. Now."

"Dean—"

Dean pulls his brother up from the chair and guides him towards the stairs, "The books will still be there in the morning."

Reluctantly, Sam allows himself to be taken to the guest room.

* * *

Scott smirks as he calms his wilding beating heart.

"Guess you're okay." He whispers as he glances at his two friends, both asleep in each other's grasp.

Stiles has one arm wrapped around Lydia's waist and Lydia is burrowed in the crook between Stile's neck and his shoulder. Both of them are asleep, blissfully unaware of anything else in the world.

When he'd received Lydia's frantic message, he'd been expecting the worst, but now, he's glad that this is a false alarm. He'll stay here for the rest of the night, just in case something happens, but for right now, he's glad that everything is okay.

"Goodnight, you two."

His friends just sleep on.

* * *

 _ **Author's Note:**_ _Next chapter, Crowley sets his plan into motion. Please review if you have a moment. Thanks!_


	5. Fear

**_Author's Note:_** _This crossover has given me a lot of trouble plot-wise. I love both fandoms so trying to write something that does them both justice is super challenging. Regardless, I'm hoping to update more frequently from now on. Please enjoy this chapter!_

* * *

 _"I don't know where you're going_

 _But do you got room for one more troubled soul?"_

 _—Fall Out Boy, "Alone Together"_

* * *

"So . . ."

Scott's voice drifts off at Lydia's death glare. The alpha then begins to chuckle and Lydia sighs, somewhat dramatically.

"Don't start with me, Scott McCall," She hisses, stirring the pot of water on her stove, wishing it would boil faster. "It's six in the morning and I have a kink in my neck."

She woke up to find herself spooning Stiles and she still isn't sure if she should be more horrified or overjoyed that she fell asleep with him on her couch. Stiles, bless is heart, is still snoring on her couch, blissfully unaware of the confusion plaguing her thoughts.

"Look, I just came because you called." Scott still has that smirk on his lips though and Lydia wants nothing more than wipe it off his face.

"And I'm grateful, but since I'm still, you know, alive, you can—" The pot still hasn't boiled and Lydia wants to bang her head against her kitchen cabinets. She needs her daily dose of caffeine and if she's going to even remotely going to try and wrap her head around the craziness of the past few days, she needs it now.

"Lydia." Scott's voice is soft, the traces of amusement now gone. He's staring at her, using those soulful eyes to try and decode her scattered thoughts. "You and Stiles—"

"There are demons and angels in the world, and you really want to ask about me and Stiles—?" She can't have this conversation now. She doesn't know the answer. She isn't sure if she wants to give one, not while she's the target of a demon king—

"He loves you, you know." Scott states much too casually.

Lydia's hand shakes, accidentally brushing the metal of the hot pot. She curses under her breath and jerks her hand away, moving towards the sink. Running the burn under lukewarm water, she sighs, "I know."

"And you—?"

"Scott, do we really need to talk about this now?" She sighs and the alpha rises from the barstool and shakes his head.

"No, we don't." Then, with a grimace, he adds, "I just . . . want you two to be happy."

He's coming from a good place, she knows that. He cares for everyone in the pack and he's just trying to help, but it's not as simple as he wants it to be.

Lydia can't fall in love right now. She can't let her guard down. People around her—those closest to her—they always end up hurt on her behalf. If something were to happen to Stiles because of her, she would never forgive herself.

Never.

For now, she can't let herself think about the way she always seeks Stiles out whenever there's a crisis. She can't spend energy trying to sort out why she feels excited whenever his hand rests in hers.

"Lydia, the water is boiling."

She snaps back into reality and turns off the burner.

"You want a cup?"

Scott shakes his head, "No. I've got to head back to Alison's."

"Oh, the hunters are staying with her?" Lydia's eyebrows furrow, "Can we trust them?"

"We don't really have a choice," Scott shrugs, "We're out of our depth here. They've dealt with Crowley before. If anyone can help us stop this, it's them."

Lydia nods, accepting the logic behind the choice, even if her mind screamed at her to stay as far away from hunters as possible. They're all in uncharted territory here, any help they could get would be great.

Even if said help came from hunters they barely knew.

"You two will come by the house when he gets up?" Scott questions and Lydia nods softly.

"Sure. Have Alison call me."

"You got it."

Silence.

"And Scott?"

"Yeah?"

Before she can regret it, she wraps her arms around him and hugs him for a brief moment, "Thank you for coming."

Scott just grins, "Anytime Lydia."

And for a brief moment, Lydia feels like a normal teenager.

* * *

"Bad cold?"

Sam jumps a bit as Alison's voice filters in through the kitchen. Upstairs, his older brother is sound asleep and Sam's a bit jealous. Even with the amount of medicine he's taking to keep his fever in check, he still can't get enough comfort to sleep more than three or four hours at a time.

"Yeah." Sam replies, unsure of how much he wants to tell the teenage huntress. There's so much more to his world than she knows about. Up until the past few days, she'd been blissfully unaware of demons and angels. Once you lose that kind of innocence, you can never really trust the world to be what you thought it should be.

"You're a pretty bad liar." She smirks as she comes into the kitchen. Moving towards the fridge, she pulls out two yogurts, and offers him one. When he begins to decline, she interjects, "If you're sick, you should eat. Medicine doesn't usually sit well on an empty stomach."

"Are you always this nice to strangers?" He feels compelled to question.

She chuckles, "Well, usually the strangers that visit us try to kill one or all of us."

The fact that she can joke about that astounds him. He hadn't been able to get much information on their backgrounds, but he does know that the pack has been through some life-threatening situations. That's supposed to change people—make them wary or angry, not smiling and joking.

"Look, Alison, my brother and I—"

"It's okay," She interrupts, taking a bite of her yogurt, "I wasn't really an ally of the pack at first either." She smirks, "That's a long story though."

"I'm sensing that." He opens his mouth to say something else, but it dissolves into coughs and soon, he's gasping for breath. His body is shutting down and sometimes—though he would never admit it to Dean—it feels like he's going to die. That, one day, he won't ever recover his breath and he'll just fade away from lack of oxygen.

But this is the price he's paying to try and shut the gates of Hell. A task that, if he succeeds, would prevent situations like the one happening in Beacon Hills from ever happening again.

Eventually, the coughing fit ends and he finds himself breathing normally once more.

Alison's concerned visage swims into his vision when she hands him a glass of water, "You okay?"

"Fine." He wipes away a bit of blood staining his lips.

"Right." Alison mumbles, not buying the lie.

"Sammy." Dean is leaning in the doorway, rubbing his eyes, clearly still half-asleep. "Y'kay?"

"I'm good, Dean. Go back to bed."

But Dean ignores him and walks into the kitchen. To Alison, he murmurs, "Got any coffee?"

"No, sorry." She answers, "But I can make a Starbucks run—"

"Dean." Castiel is suddenly standing in the middle of the kitchen and the trio nearly jumps from the angel's abrupt entrance.

"Jesus, Cas, you need to make—"

"Dean, it's Crowley." The angel's voice is strained, tinged with worry.

"What about him?" Alison presses.

"He's found the third key. It's the blood of an Alpha werewolf—"

The color drains from Alison's face and she quickly pulls out her phone, "Oh, God, Scott!"

"How do you know this?" Sam demands.

"I can't get ahold of Scott!" Alison quickly redials and the huntress is nearly in tears, not that Sam can blame her.

"Where was he headed?" Dean faces her, placing a hand on her shoulder, trying to keep her in the moment.

"To Lydia's. He got a phone call from her—"

"Okay, we just need to—"

"Alison?" Scott calls, the sound of a door slamming behind him. "Lydia wants you to—" Coming into the kitchen, he notices his former girlfriend's distraught expression and immediately stiffens, "Are you okay? What's wrong?"

Alison embraces him, a tear rolling down her cheek, "I'm fine. We just thought Crowley had gotten you."

"Crowley? What does he want with me?"

A shrill phone ring interrupts the conversation and Scott pulls out his device, only to tilt his head to the side in confusion.

"What?" Sam asks.

"It's nothing. Just a number I don't recognize—"

Dean snatches the phone and answers it, "Yeah?"

 _"Hello Dean."_ Crowley's voice is on the other line and Dean can picture the King of Hell reclining back in his chair, smirking at the two brother's incompetence. _"Didn't know you were a secretary too. Taking other people's phone calls?"_

"What do you want Crowley?" Dean growls, placing the call on speaker.

 _"Bring me the angel, the banshee and the alpha to the high school auditorium by 8pm tonight."_

"Not going to happen Crowley." Sam informs the demon, his voice strong and unyielding.

 _"Figured you'd say that. Oh, well, thought I could try. Bye boys."_ A pause. _"Oh, and Scott? Derek and Isaac say hello."_

And then the line goes dead.

* * *

 ** _Author's Note:_** _Please review if you have a moment. Thanks!_


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